Controlling Skyrmions

Magnetic skyrmions—tiny vortex patterns of spins—hold promise for information storage because of their robustness to perturbations. Skyrmions have been observed experimentally, but manipulating them individually remains a challenge. Romming et al. (p. 636; see the cover) used spin-polarized electrons generated by a scanning tunneling microscope to reversibly create and destroy skyrmions in a thin iron film covered by a layer of palladium. The energy of the tunneling electrons was the decisive factor determining the probability of the process; atomic defects in the film acted as pinning sites for the skyrmions. The work demonstrates the feasibility of using spin-polarized tunnel currents for the controlled manipulation of individual skyrmions.

Abstract

Topologically nontrivial spin textures have recently been investigated for spintronic applications. Here, we report on an ultrathin magnetic film in which individual skyrmions can be written and deleted in a controlled fashion with local spin-polarized currents from a scanning tunneling microscope. An external magnetic field is used to tune the energy landscape, and the temperature is adjusted to prevent thermally activated switching between topologically distinct states. Switching rate and direction can then be controlled by the parameters used for current injection. The creation and annihilation of individual magnetic skyrmions demonstrates the potential for topological charge in future information-storage concepts.